1729 divisible by 7 is true or false?

We need to double the last digit of the number and then subtract it from the remaining number. If the result is divisible by 7, then the original number will also be divisible by 7.

In the number 1729 , double the last digit of the number 9 is 18. 172 – 18= 154. double the last digit of the number 4 is 8. 15 – 8= 7 [Now we need to subtract it from the rest of the remaining number]
Since 7 is divisible by 7.
Hence, 1729 is also divisible by 7.